This application is a division of application Ser. No. 10/038,682 filed Jan. 8, 2002, now U.S. Pat. No. 6,932,820 the entire content of which is hereby incorporated by reference in this application.
The present invention relates to a spinal fixation device for spinal fusion and particularly relates to a uni-directional anterior cervical spinal fixation plate device for progressively maintaining a bone graft between adjacent vertebrae under compression.
Spinal plates have been developed for stabilization of the spine upon spinal fusion. Conventional anterior cervical spinal fixation plates typically comprise a unitary plate having a pair of bone screw openings at each of its opposite ends. The plate has sufficient length to span an excavated bone graft-receiving site in the vertebral column and in which site a bone graft is located for fusion to adjacent vertebrae. These prior anterior cervical fixation plates fix the adjacent vertebrae on opposite sides of the bone graft-receiving site relative to one another. It will be appreciated, however, that with both ends of the unitary plate secured by screws to the adjacent vertebrae, advantageous and beneficial compression of the bone graft between the adjacent vertebrae and during the fusion process cannot be obtained. While it has been recognized that compression of a bone graft is desirable over time as the graft fuses to the vertebrae, the nature of these unitary anterior cervical spinal plates fixed at opposite ends to the adjacent vertebrae precludes compression of the bone graft beyond any initial compression during the surgical procedure. Consequently, there has developed a need for a spinal fixation device in which the bone graft can be progressively compressed between adjacent vertebrae over time.